Wide range inductively-tuned oscillator



' 1 sept 8 953 J. J. EBERs v 2,651,738

WIDE RANGE, INDUCTIVELY-TUNED OSCILLATOR Flled July 12, 1951 2 Sheets-Sheet l wugfg 3/ il a l INVENToR.

A froh/vf Y Patented Sept. 8, 1953 WIDE RANGE INDUCTIVELY-TUNED OSCILIATOR Jewell J. Ebers, Columbus, Ohio, assignor to The Ohio State University Research Foundation, Columbus, Ohio, a corporation of Ohio Application July 12, 1951, Serial No. 236,407

Claims.

My invention relates broadly to high frequency oscillator systems and more particularly to a wide range high frequency oscillator and waveguide system.

One of the objects of my invention is to provide a construction of wide range high frequency oscillator and waveguide which is adjustable over a wide frequency range and which has a high degree of efciency.

Another object of my invention is to provide a construction of inductively tuned high frequency oscillator and waveguide for efficient short-wave generation.

Still another object of my invention is to provide a construction of high frequency oscillator and waveguide including means within the oscillator for changing the volume of the cavity in the oscillator and waveguide for correspondingly changing the frequency of operation thereof.

Still another object of my invention is to provide a construction of adjustable plunger and arrangement of adjusting means therefor in the cavity of a high frequency oscillator and waveguide for controlling the frequency of operation of the oscillator and waveguide.

A further object of my invention is to provide a construction of wide range inductively tuned high frequency oscillator and waveguide including a capacitative system for preventing energy loss through the top of the waveguide and at the same time provide electrical insulation so that a negative voltage can be applied to the repeller of the oscillator.

Still another object of my invention is to provide an arrangement for mounting an adjustable plunger with respect to the cavity of a high frequency oscillator and waveguide through a capacitative support which prevents energy loss out through the top of the waveguide and at the same time provides electrical insulation so that a negative voltage can be applied to the repeller.

Other and further objects of my invention reside in the assembly and arrangement of adjustable plunger in the cavity of an inductively tuned retarding-eld high frequency oscillator and waveguide as set forth more fully in the specification hereinafter following by reference to the accompanying drawings in which:

Figure 1 is a vertical sectional view through a wide range inductively tuned oscillator and waveguide constructed in accordance with my invention with certain of the parts shown in elevation; Fig. 2 is a vertical sectional view taken substantially on line 2 2 of Fig. 1 and illustrating the exterior of the cavity and the adjustable bellows which serves to adjustably mount the movable plunger, in side elevation; Fig. 3 is a transverse sectional view taken substantially on line 3 3 of Fig. l; Fig. 4 is a transverse sectional view taken substantially on line of Fig. l; Fig. 5 is a transverse sectional view taken substantially on line r3-5 of Fig. l, illustrating particularly the decoupling section of the waveguide; Fig. 6 is a transverse sectional View taken substantially on line ii-ii of Fig. l and illustrating particularly the adjustable plunger within the cavity; Fig. 7 is a transverse sectional view taken substantially on line l--l' of Fig. l and illustrating particularly the anode aperture of the electron gun; and Fig. 8 schematically illustrates the application of the oscillator and waveguide of my invention in an impedance testing circuit.

My invention is directed to a method of utilizing the power which is normally lost past the plunger in the cavity of a wide-tuning-range oscillator. All inductively tuned tubes, that is, tubes tuned by changing the volume of a cavity with a plunger heretofore known, utilize either a contacting plunger or a choke type plunger with which there is associated a certain amount of power loss. The power output from the tube is then obtained by means of a coupling loop into the cavity resonator or by means of an iris opening into a waveguide from the cavity resonator.

In the drawings have shown a tube in which the energy from the resonant cavity l which leaks past the tuning plunger 2 is used to excite a waveguide output 3. The tube is rotationally symmetric about a center-line @l except for the rectangular waveguide output Electrons are supplied by the electron gun E and are accelerated through the anode aperture c and then interact with the radio frequency eld of the resonator gap l. For a single cavity oscillator, the radio frequency producing mechanism can be of two types:

(a) reflex klystron (b) retarding-eld oscillator The shape of the plunger 2 can be varied as well as the spacings between the plunger and the inner and outer walls of the cavity resonator l to provide a good impedance match from cavity l to waveguide 3 over a wide frequency range. Plunger 2 is adjustable to various positions within cavity i3 and the decoupling member i3d which is coextensive therewith. The decoupling member i3d projects from the cavity resonator l into the waveguide 3 for a distance substanf tially one-half the distance between the spaced 3 walls or" the waveguide. Energy is almost cornpletely prohibited from being lost out the top side of the waveguide 3 by means of a mica bypass condenser 8.

The plunger 2 can be moved by either of three methods:

(A) the method illustrated utilizes a movable member 9 extending down the center or" the inner conductor IG of the cavity resonator' 3. A pin of insulation material 9a is inserted through a transverse aperture II in the movable member 9 through slots I2 in the inner conductor I@ and iinally through a transverse aperture 2a. in the tuning plunger 2. The movable member S can then be adjusted by means of bellows ifi from the outside of the tube. Bellows ill serves as a mounting means for the flange I5 of member I6 which has integrally formed tubular portion II within which the at disc-like insulator lf; is arranged. Movable member 9 is supported by iiat disc-like insulator IB and extends upwardly to a suitable control means for projecting or retracting the movable member 9 within the limits allowed by the bellows I and the slots l2 in inner conductor it. Plunger 2 is correspondingly adjusted Within the interior wall of cavity I3 and the decoupling member i3d coextensive therewith. rThis method however is not applicable in the case of a reflex lrlystron.

(B) the second method is to provide inea-ns to move the plunger 2 through rods of insulation material extending through slots formed in the outer conductor I3 of the cavity.

(C) the third method is to provide an arrangement of rods or insulation material directly fastened to the top of the plunger 2 through apertures in the top side of the output wave guide Il.

lt will be understood that appropriate vacuum seals are provided at the top and bottom of the tube as well as in the out-put waveguide and that thevdrawings are for the purpose oi illustrating the coaction and association of the several elements rather than the manner of vacuum 'sealing the parts.

It is also to be understood that the shorted section of 3a `guide tothe left of the decoupling section i3d 'shown in Figs. l, 2 and 5 presents an infinite impedance to the decoupling section i3d.

The mica byepa'ss condenser s which serves as the support for the inner conductor iii of the cavity resonator consists of a metallic plate which is secure/d to the external surface of the inner Vconductor I9 for mounting the inner conductor lli in a vertical position on an axis passing through the electron gun assembly. The metallic plate Ga is mounted in insulated relation to the top plate of the waveguide 3. The top plate seis 'centrally apertured at 2te and is provided with an annular recess 2th disposed 4concentricall'y above the central aperture 2Go in the top plate 2G. The recess 2do serves as a set for the sheet-like ring of insulation material 2E. l prefer to use mica in this position. The metallic plate Sa is seated upon the ring of insulation material 2l so that the plane Aof the top of the metallic plate 'Ba is substantially 'coplanar with the plane of the top of the top plate 20. A similar ring of insulation material 'such as mica indicated at 22 extends over the top of the metallic plate to and over the top of the top plate 2@ and is secured in position by means of screws 23 which pass through the metallic binding ring 24 and through the ring 'of insulation material 22 for securing metallic plate Sa in position with respect to the top plate 2o 4but electrically insulated therefrom. The metallic plate 8a which is connected with the exterior of inner conductor l0 is of substantially smaller diameter than the diameter of the recess 20h in top plate 20 so that an annular gap 20c is maintained between the external periphery of the metallic plate 3a and the interior of the recess 23h when the inner conductor Iii is properly centered with respect to the cavity. The metallic plate 8d may be copper as a high degree of conductivity is desirable. When the metallic plate Sa is clamped in position between the mica sheet-like rings 2i and 22 and properly centered with respect to the cavity an electrical by-pass condenser is provided which prevents energy loss out through the top of the waveguide and at the same time provides insulation so that a negative voltage can be applied to the repeller constituted by inner conductor I. ri'he high frequency circuit is completed from the exterior of the waveguide through the capacitive transverse path which is established between the bottom portion of the recess 26D and the metallic plate Sa through the ring of insulation material 2l and through the metallic binding ring 25, connected to top plate 2u through screws Ain the capacitative path between the top of metallic plate Sa and the overlapping portion of the metallic binding ring 2li.

The electron gun 5 has the cathode thereof excited from heater winding 25, the cathode being provided with a shaped surface 5a for directing electrons through the beam focusing element formed by aperture plate shown generally at 25 mounted in insulated relation to the cavity l by means of the spacer member of insulation material represented at 21. The spacer member of insulation material at 21 ts within the recess 23 of the cavity I and against the plate 2i? that carries the anode aperture 6. The cathode system is thus electrically isolated from the beam focusing element or elements and from the anode aperture 6 enabling an electron discharge to be established between cathode 5o and the anode aperture and the end of the repeller I? through resonator gap l. The capacitative relationship of the plunger 2 with the interior surface of resonant cavity l and the decoupling member I'a is variable over the range heretofore explained as limited by the length of the slots I2 in inner conductor I0 and the abutment of the pin of insulation material I I at either end of the path of travel thereof; as well as the ability of the bellows UI to expand and contract for enabling the movable member 9 to be raised and lowered from the exterior of the tube.

In Fig. 8 I have shown an application of the composite high frequency oscillator and waveguide of my invention where the tube of my invention is represented generally at 30 and the waveguide portion thereof represented at 3|. The composite structure is shown connected through attenuator 32 and the frequency meter section illustrated at 33 which in turn connects through attenuator 34 with the slotted section impedance meter 35 to the impedance 36 under test. While I have illustrated but one application of my invention it will be manifest that there are many applications of the system of my invention as it replaces a series of tubes and is usable as an oscillator and high frequency propagator generally in both transmitters and receivers in micro-wave communication systems; antenna measurements; and in all instances where a wide range of useful high frequency oscillations are required.

I have successfully operated the tube and waveguide system of my invention for the production of power outputs in excess of l Watt over a range of 4.0 to 7 .2 centimeters.

I have found the tube system and waveguide as set forth herein highly practical in its production and operation but I realize that modifications may be made in structural details and I desire that it be understood that no limitations upon my invention are intended other than may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is as follows:

i. A high frequency oscillator and waveguide comprising in combination with a waveguide, a resonant cavity associated with said waveguide, an electron discharge source arranged adjacent said resonant cavity and said waveguide, an inner conductor extending through said waveguide and terminating adjacent said electron discharge source, means for supporting said inner conductor in capacitative relation to said waveguide, an adjustable member extending through said inner conductor, a toroidal shaped member surrounding said inner conductor and insulatingly supported by said adjustable member, said toroidal shaped member being Variably displaceable in a direction normal to the axis of said waveguide in spacial relation to said inner conductor in both said cavity and said waveguide, and a decoupling member extending from said cavity into said waveguide .and surrounding the path of travel of said toroidal shaped member.

2. il combined high frequency oscillator and waveguide comprising a waveguide, a resonant cavity connected with said waveguide, means for directing an electron beam through said resonant cavity transversely of said waveguide, an input for said waveguide and an adjustable plunger variably movable between said means and the input of said wavegui-de and a decoupling member coextensive with said resonant cavity and extending into said` waveguide and surrounding the path of movement of said adjustable plunger.

3. .en oscillator and waveguide comprising in combination with a waveguide having an input section and an output section, a resonant cavity located adjacent said input section, means for projecting an electron stream through said cavity, a tuning plunger interposed between said means and the input section of said waveguide for adjusting the frequency of operation of said oscillator and resonant cavity and a cylindrical decoupling member coextensive with said cavity and extending into said waveguide and surrounding the path of movement of said tuning plunger.

e. An oscillator and waveguide comprising in combination with a waveguide having input and output sections, a resonant cavity associated with said waveguide, means for directing an electron stream through said resonant cavity and tuning means displaceable through said resonant cavity and in a path normal to the axis of said waveguide adjacent the input section thereof for adjusting the frequency of operation of said resonant cavity and a decoupling member projecting out of said cavity and into said waveguide and surrounding the path of movementoi said tuning means.

5. An oscillator and waveguide system comprising in combination with a waveguide having input and output sections, a resonant cavity associated with said waveguide adjacent said input section, means for projecting an electron stream through said resonant cavity and in a path normal to the axis of said waveguide, a tubular conductor extending through said waveguide and into said resonant cavity, said tubular conductor having slots in the portion thereof which projects into said resonant cavity, an adjustable rod projecting through said tubular conductor, and a toroidal shaped tuning plunger insulatingly supported on means extending through said slots and carrier by said adjustable rod, whereby said toroidal shaped tuning plunger may be adjusted to positions within said resonant cavity adjacent the input section of said waveguide for selectively adjusting the frequency of operation of said resonant cavity and a circular decoupling member projecting from said cavity and extending into said waveguide and encircling the path of movement of said toroida1 shaped tuning plunger.

6. An oscillator and waveguide comprising a waveguide having an input section and an output section, an electron discharge means having its axis extending in alignment with a center line through said waveguide adjacent the input section thereof, a cavity resonator disposed about said electron discharge means, means for tuning said cavity resonator for matching the impedance and said cavity resonator to said waveguide over a wide frequency range and a cylindrical decoupling member ooextensive with said cavity resonator and projecting into said waveguide and encircling the path of movement of said means for tuning said cavity resonator.

7. A composite electron discharge means and waveguide comprising a waveguide having an input section and an output section, an electron discharge tube arranged on an axis extending transversely of said waveguide adjacent the input section thereof, a cavity resonator surrounding said electron discharge means, a tubular member extending through said waveguide to a position spaced from said electron discharge means, said tubular member having diametrically aligned slots therein adjacent the end thereof, a rod member extending through said tubular member, a cylindrical toroid disposed in spaced relation to said cavity resonator and to said tubular member, means extending through the slots in said tubular member for insulatingly supporting said cylindrical toroid on said rod member, said cylindrical toroid being movable to selective positions within said cavity resonator for selectively adjusting the frequency of operation of said resonant cavity and a cylindrical decoupling member coextensive with said cavity and projecting into said waveguide and surrounding the path of movement of said cylindrical toroid.

8. A composite electron discharge means waveguide as set forth in claim '7 in which one end of said tubular member is supported on said waveguide and. wherein said rod member is supported on a bellows-like device carried by said waveguide, whereby said rod member may be adjusted in a linear direction through said tubular member.

9. A composite electron discharge means and waveguide as set forth in claim 7 in which said tubular member is insulatingly and capacitatively supported with respect to said waveguide, and wherein said rod member is supported on a flexible bellows with respect to one side of said waveguide.

10. A composite electron discharge means and waveguide as set forth in claim 7 in which said tubular member is jcap'acitatvely mounted with respect to one wall of said waveguide land in which 'a nexible bellows Vmourited on one wall of said waveguide concentrically and insulatingly surrounds said rod member and supports said rod member for axially longitudinal adjustment with respect to said tubular member.

11. A composite electron discharge 4means and waveguide as set forth in 'claim 7 in which said tubular member is supported by a flat electrically conductive disc extending in a plane normal 'to the axis of said tubular member and wherein dielectric sheets supported with respect to one wall of said waveguideserv'e to grip and support said electrically conductive pla'te and serve as a 4capacit'ative coupling vtherefor with respect 'to the wall of the waveguide vand iiexible means for supporting said rod'me'mber vfor adjustment with respect to said tubular member.

l2. A composite electron discharge means and waveguide as set forth in claim 7 in which-said waveguide has the upper portion thereof apertured adjacent the input end thereof, a plate closing the apertured portion of the waveguide, said plate having'an annular recess therein, an annular dielectric sheet supported in said recess, a conductive plate secured to said tubular member and supported 'in capacitative relation to said waveguide vand extending over said-annular dielectric sheet, an annular dielectric sheet mounted on said'plate and extending over said conductive plate, a 'conductivesheet electrically connected with's'aid rst'inentioned plate and extending over 'said secondmentioned dielectric sheet vand electrically connected with the said plate and capacitatively connected with said conductive plate and forming a Vcapacitative path from said waveguide Vthrough said tubular member.

13. In a device of the class described a waveguide formed by a pair of spaced Walls and having input and output sections, an oscillator, a resonant cavity connecting said oscillator with the input section of "said waveguide, means extending through one wall of saidwavegnide for adjusting the effective impedance of said resonant cavity with respect to said waveguide and a capacitative support'for said means at the location at which the aforesaid means extends through said waveguide and a decoupling member connected with said cavity and projecting into said waveguide and surrounding the path through which saidmeans is adjusted.

14. A composite electron 'discharge means and waveguide comprising a waveguide having an input section and an output section, an electron discharge tube arranged on an axis extending transversely of said waveguide adjacent the input section thereof, a cavity resonator surrounding said electron discharge means, a tubular member extending through said waveguide to a position spaced from said electron discharge means, a ilat electrically conductive disc attached to said tubular member adjacent one end thereof, dielectric sheets supported with respect to one wall of said waveguide and forming mounting means for said electrically conductive disc and serving 'as a capacitative coupling therefor with respect to the Wall 0f the waveguide, said ltubular member having diametrically aligned slots therein adjacent the other end thereof, a rod member extending through said tubular member, means for exibly supporting said rod member for lineal adjustment through said ktubular member, a cylindrical toroid disposed in spacedrelation to said cavity resonator and to said tubular member, means extending through the slots in said tubular member for insulatingly supporting said cylindrical toroid on said rod member, said cylindrical toroid being movable to selective positions within said cavity resonator for selectively adjusting the frequency of operation of said cavity resonator.

15. A composite electron discharge means and vwaveguide comprising a waveguide having an upper and lower wall portion forming an input section and an output section, said upper wall portion being apertured adjacent the input end of said waveguide, a plate closing -said apertured upper wallportionfsaid plate having an annular recess'therein, an annular dielectric sheet supported-in-saidrecess, anelectron discharge tube arranged on an axis extending transversely of waveguide adjacent vtheinput section thereof, a cavity resonator'surroun'ding saideloctron discharge means, a tubular member extending through waveguide tota position spaced from said-electron discharge means, a conductive plate securedto-saidltubular member and extending over said annular dielectric sheet, another annular dielectricrsheet peripherally supported by said plate andprojecting over said conductive plate, an electrically:conductive annular sheet electrically connected with said first-mentioned plate andfextending over said second-mentioned dielectricsheetand capacitatively coupled with said conductive plate and'iorming a capacitative path romsaid .waveguide through said tubular member, saidl tubular .member i having diametri- 'callyaligned'slotstherein adjacent. the end thereof, a rod member extending through said tubu- `lar member, a cylindrical toroid disposed in spaced relation to said cavity resonator and to said tubularniember, means extending through the slots in' said'. tubular; member for insulatingly supporting said `cylindrical toroid on said rod member, said vcylindrical'.toroid.being movable 'to .selectivegpositions within said vcavity resonator for selectivelyadjusting the frequency 'of operation of. saidlcavityV resonator.

.JEWELL J. EBER'S.

References Cited in theffilef'of this'patent UNITEDSTATES PATENTS vNumber Name Date '2,422,465 VBondley June 17, 1947 2,502,531 Morton. et al Apr. 4, 1950 2,508,573 Hulstede May 23, 1950 v2,523,031 VLai'erty Sept. 19, 1950 '2,530,836 Mumford Nov. 21, 1950 

